Remove base::underlying_type, replace uses with std::underlying_type

base/template_util_unittest.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "base/template_util.h"
 
 #include <string>
 
 #include "testing/gtest/include/gtest/gtest.h"
 
@@ skipping 51 matching lines @@
 static_assert(!internal::SupportsOstreamOperator<SimpleStruct>::value,
               "simple struct should not be printable by value");
 static_assert(!internal::SupportsOstreamOperator<const SimpleStruct&>::value,
               "simple struct should not be printable by const ref");
 static_assert(internal::SupportsOstreamOperator<StructWithOperator>::value,
               "struct with operator<< should be printable by value");
 static_assert(
     internal::SupportsOstreamOperator<const StructWithOperator&>::value,
     "struct with operator<< should be printable by const ref");
 
-// underlying type of enums
-static_assert(std::is_integral<underlying_type<SimpleEnum>::type>::value,
-              "simple enum must have some integral type");
-static_assert(
-    std::is_same<underlying_type<EnumWithExplicitType>::type, uint64_t>::value,
-    "explicit type must be detected");
-static_assert(std::is_same<underlying_type<ScopedEnum>::type, int>::value,
-              "scoped enum defaults to int");
-
 struct TriviallyDestructible {
   int field;
 };
 
 class NonTriviallyDestructible {
   ~NonTriviallyDestructible() {}
 };
 
 static_assert(is_trivially_destructible<int>::value, "IsTriviallyDestructible");
 static_assert(is_trivially_destructible<TriviallyDestructible>::value,
               "IsTriviallyDestructible");
 static_assert(!is_trivially_destructible<NonTriviallyDestructible>::value,
               "IsTriviallyDestructible");
 
 }  // namespace
 }  // namespace base